Optimal Switching Control Of Auxiliary Circuit Paralleled Boost Converter For Load Transient

Boost converters are widely used in various direct current boosting applications as a basic DC-DC converter topology.Due to the non-minimum phase characteristics of the Boost converter,the control effect on improving its load transient performance has been unsatisfactory.The time-optimal control method can theoretically realize the fastest load transient adjustment reaching to the new steady-state operating point by switching once.Based on this,it is proposed to explore the load transient performance enhancement technology of Boost converter from the perspective of topology and control compound adjustment.The main contents of the study are as follows:Firstly,the steady state controller of time-optimal control for the Boost converter is designed to solve the secondary adjustment problem when using traditional PID control as the steady state controller.The time optimal control based on capacitor charge balance and its control principle of switching between dynamic and steady states are introduced.When the PID control is used as the steady-state controller,the converter has a secondary adjustment transition phenomenon that deviates from the steady-state operating point after the ending of transient.In order to avoid this transition phenomenon,the inductor current ripple-based hysteresis control is constructed as the steady state control from the perspective of eliminating the DC offset of the control signal.Through simulation and experimental verification,there is no secondary adjustment of the designed time-optimal control for Boost converter,which can complete the time-optimal dynamic adjustment process during the load transient.Secondly,the optimal switching control of auxiliary circuit paralleled Boost converter for load transient is proposed,in order to further improve the load transient performance of Boost converter on the basis of time optimization.The auxiliary circuit structure is introduced,which based on the capacitor charge balance algorithm,and the mathematical derivation of the optimal switching time of the auxiliary circuit during the load transient is derived.The selection principle of the inductor,the fall and overshoot of the output voltage adjustment are discussed.Design the controller and give a concrete digital-analog mixed implementation.The proposed control breaks the basic Boost main circuit parameter limitation,and has been verified to achieve faster load transient response than time-optimal control.Finally,in order to reduce the output voltage regulation and input current overshoot of the auxiliary circuit paralleled Boost converter,a sequence switching control strategy is proposed.The control sequence is analyzed and derived from the geometrical point of view,and the construction principle and implementation steps of the control algorithm are explained.In addition,the relationships between the number of auxiliary circuit switching,inductance selection,and load step variables are discussed.Compared with the optimal switching control for auxiliary circuit,the control strategy solves the problems of large voltage regulation and input current overshoot,improves the output voltage accuracy of the Boost converter under transient conditions,and further improves the load transient performance of Boost converter.